What sign might indicate a serious head injury in a patient?

Battle's Sign is a clinical indicator that can suggest a serious head injury, particularly a skull fracture. This sign is characterized by bruising around the mastoid process, which is located just behind the ear. It typically occurs due to blood collecting in the tissues surrounding the temporal bone as a result of trauma, which may indicate that there is an underlying skull fracture.

Recognizing Battle's Sign is critical for medical professionals, as it implies that the injury could be severe and may involve the underlying structures of the brain. Rapid identification and appropriate intervention are vital for the patient’s outcome, especially given the potential for complications such as intracranial hemorrhage.

The other options, while relevant in a broader context of assessing a patient's neurological status, do not specifically indicate a serious head injury. Checking for pulse is important for evaluating circulation rather than direct head trauma. Assessing extremity movement helps evaluate motor function but does not directly point to a head injury. Similarly, a response to stimuli can gauge overall neurological function but is not as definitive as identifying physical signs such as Battle's Sign.